Various combinations of surfactants are exemplified by U.S. Pat. Nos. 4,381,259 to Homma et al, 4,265,782 to Armstrong et al, and 4,375,421 to Rubin et al. The Homma et al patent is directed to a shampoo composition employing an anionic phosphoric acid ester surfactant, a cationic polymer, and at least one other surfactant that may be an anionic organic surfactant other than the phosphoric acid ester surfactant, a nonionic organic surfactant, or an amphoteric organic surfactant. Armstrong et al describe a relatively high viscosity, detergent composition that includes a modified rosin ester and at least one other surfactant selected from anionic, nonionic, cationic and amphoteric surfactants. The Rubin et al patent pertains to viscous compositions containing amido betaines and salts, which may additionally contain about 2.5 to 4.0% of a micelle-forming anionic surfactant.
Conventional printing blankets in use throughout the printing industry, in particular in offset lithography, are made with a vulcanized elastomeric face, which may be a soft rubber, and a fabric backing, which is typically a multi-ply, woven cotton fabric. In offset lithography, these blankets serve to transfer printing ink from a printing plate to paper being printed. During this ink transfer, intimate contact between the contacting surfaces is essential. Intimate contact is ordinarily achieved by positioning the blanket-covered cylinder and the cylinder it contacts, so that the printing blanket is compressed throughout the ink transfer.
However, a problem is that a blanket used to print envelopes generally cannot thereafter be used to print paper, as ghosts of the envelope will appear on the paper sheets. Moreover, misfeeds occasionally occur in which extra sheets of paper cause a "smash," that is, a permanent, impact-caused compression of a portion of the fabric backing of the blanket. Typically, the elastomeric blanket face is not marred or broken by a smash.
Because of known drawbacks to conventional printing blankets, there are improved blankets such as the compressible offset printing blanket of U.S. Pat. No. 4,042,743 to Larson et al, the smash-resistant offset printing blankets of U.S. Pat. No. 3,285,799 to Peterson and U.S. Pat. No. 3,881,045 to Strunk, and the smash-recoverable printing blanket of U.S. Pat. No. 4,086,386 to Gaworowski et al. The Gaworowski et al printing blanket contains microcapsules disposed in a layer thereof, which when the blanket is smashed, release a liquid that causes the layer to swell and that thereby effects blanket restoration. The liquid may be water or a water solution, and is described as being any suitable liquid that produces swelling or expansion of the fabric layers with which it comes into contact.
Nevertheless, the conventional printing blanket remains in wide use, and if for one reason or another the blanket becomes unsuitable for further use even though its elastomeric face is not marred or broken in any way, it is removed from the cylinder and replaced. Therefore, there is a need for a composition for restoring a conventional printing blanket having an unmarred or unbroken elastomeric face but in need of restoration, in particular a smashed printing blanket. Such a composition would be remarkable if it could provide more than a few additional hours of useful press life. Furthermore, if for at least 5% of the smashes, a blanket treated with the composition prior to being smashed, would be restored by the prior-applied composition, the composition would provide an even greater contribution to the art. Such a composition should be non-injurious to the elastomeric blanket face, and would be especially advantageous if it could be easily and safely applied to the blanket. In addition, such a composition would provide an improved method of restoring a conventional printing blanket having an unmarred or unbroken elastomeric face but in need of restoration.